Ignition-voltage control for internal-combustion engines



May 6., 1924.

J. B. BUSHNELL IGNITION VOLTAGE CONTROL FOR INTERNAL COMBUSTION ENGINES Filed Auz. 15. 1921 "III In- JIMMMMY To Derrmswroz.

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-4 ATTORNEYS Patented May 6, 1924.

UNITED STATES "PATENT.OFFICE;

JOHN B. BUSHNELL, or 'BERKELnnonLIFoRNIA.

IGNITION-VOLTAGE CONTROL on INTERNALLCOMBUSTION, ENGINES.

Application filed August 15, 1921. Serial No. 492,606.

T 0 all whom it may concern: Be it known that I, JOHN B. BUSHNELL,

a citizen of the United States, and a The invention relates to a device for controlling the voltage of the ignition spark in internal combustion. engines equipped with storage battery ignition systems.

In such systems, as ordinarily used, the

voltage of the spark remains constant, irrespective of the richness of the fuel orits rate of consumption. If, as is usually the case, the spark voltage is of the propervalue for ordinary conditions of operation, then var1at1ons from these conditions cause the spark intensity or voltage to be imthe fuel to burn quicker than if a lean spark, or one produced by a relatively low voltage, is used. This effect is quite generally recognized, although of course the particular condition of the fuel itself has an effect upon the speed of combustion. As a concrete example, assume that the engine is running slowly with little load, the throttle being almost closed. Under such circumstances a fat spark is not objectionable, since the fuel mixture is lean, and therefore no undue violence of explosion can be obtained. Under full load, when the engine is rotating at high speed, and the throttle is open, a fat spark is advantageous for it is essential that the fuel be burned as rapidly as possible was to eliminate as far as possible the waste of fuel and to obtain maximum power from the engine.

When it is attempted to change from one mode of operation to another, that is, when the throttle is opened so as to speed up the engine and make it take more load, the temporary transition period produces conditions which make a fat spark highly undesirable. When the throttle is opened the richness of the fuel is increased, but for the moment there is no corresponding increase in the speed of the engine. Instead there is merely a steady acceleration. The fat spark in conjunction with the rich fuel, causes very rapid combustion in the cylinders. The engine running comparatively quences.

, slowly, theviolence of the explosion is not,

taken up by the movement of the piston, but instead there areexcessive strains produced in the operating parts of the engine. The strains produced in this way if long maintained, are very apt to haveserious consevention, to prevent these strains by so regulating the intensity of the spark that during these transition periods the spark has low intensity. I accomplish this result by placing a variable resistance in series in the high tension ignition circuitand increasing this resistance when the combustible mixture charge is too heavy for the engine speed. 1

When an. internal combustion engine is operating, a reduction of pressure or partial vacuum is produced in the inlet manifold above theqthrottle. When the throttle is suddenly opened, this partial vacuum is greatly reduced, so that an overcharge of mixture is accompanied by a reduction of vacuum in the inlet'manifold, and I employ this reduction of vacuum to decrease the voltage of the ignition spark; As soon as the speed. of the engine increases, due. to the throttle opening, the vacuum is again produced in the inlet manifold and the voltage of ignition spark raised.

It is therefore another object of my invention to vary the spark voltage in response to the pressure conditions in the inlet manifold of an engine.

In the accompanying drawing, I have shown one form of device for accomplishing this result, but it is to be understood that I do not limit myself to such form, since the invention, as set forth in the claims, may be embodied in a plurality of forms.

The drawing is a longitudinal section of a device embodying my invention,- in its environments.

The device comprises a closed casing 2, adapted to be connected to the inlet manifold of an internal combustion engine, so that the same conditions of pressure exist therein as in the manifold. Arranged in the casing and insulated therefrom and from each other, are two electrodes 34, the adjacent ends of which are spaced apart slightly, for instance, one-sixteenth of an It'is one of the objects of-myincasing, that is, at atmospheric, pressurethe resistance is greater than when a partial vacuum exists in the casing. The electrodes are connected in series, the high tension ignition conductor, preferably between the coil and the distributor, so that a variable resistance is thus interposed in the high tension ignition circuit. When the throttle is suddenly opened, the pressure in the easing increases, increasing the resistance ofthe air gap and decreasing the tension of the ignition spark Y I claim: I

1. The method of Varying the Voltjage'o f an ignition spark of an internal combustion engine provided with batjt ery'ignition which comprises varying the resistanceof the'Pigni'- ti'on circuit in accordance with variations ii i' pressure in the inlet manifold ofthe enigi 2; In an internal"combustionengine' hay:

mg a fuel intake, 'a n" ignition circuit, a source of substantially constant ie'lecjtr'ome tiveforce for-the circuit, the method' nfnom pensati'ng for varying conditions of f opera tion of the engine, Which comprises vary'in J the resistance of I the ignition" circuit rincordance with the vali a tlO l l in pressure inthe fuel intake. H v

3. In an internal combustion enginehaving a fuel intake, 'an 'i'gnitionjcircuit,"and"a; source of substantially constantelectrome' tive force for the circuit, the IIIthOdOf CO1 n 'pensating for varying conditions of opera; tion' of the enginefwhich compri s'tinereas ing the resistance of the ignition circuit-"in accordancewith the" increase.- i'n pressure the fuel intake,

surevar iations produced in the manifold are communicatedto the chamber and a pair of spacedelectrodes in said casing connected in the ignition circuit;

6.- 'I'n coinbination, aninternal combustion engine having a fuel i'r-iilet, an: ignition .cir-

cuit for the engine, a source of substantially con's'tantelectromotive force for the circuit, and means ifor varying the resistance of the circuitiin accordance with variations pres- Sui"? inf'tll'e 'fuelinlet;

7; e The combination with an internal oom bustion enginehaVing a battery ignitionsyste in the ignition circuit; I 18. In an" internal combustion eng ne, spark rgnitlon system,- a fuel inlet, and

of a closed casing cominunicatingjwith the' inlet man fold of the engine and spaced electrodes" in said casing; connected series means-for varyingathe voltage across the sparkf 'in response to the pressure variations in the inlet! Imtest-imon-y whereof, I have.- hereunto set mjhand; v v

1 B. BUSHNELL 

